1. Field of the Invention
The present invention relates to a semiconductor device using a hollow region and a porous silicon layer, and to a method of manufacturing the same.
2. Description of the Related Art
A device using an SON (Silicon On Nothing) structure has been proposed in order to improve semiconductor device performance. The device operation is now being inspected using a μm-order single SON structure. Thus, in order to realize practical use as large-scale integrated circuit (LSI), the μm-order SON structure must be arranged and formed vertically and horizontally.
A method using hydrogen annealing is give as the method of forming a micro SON structure (T. Sato “A New Substrate Engineering for the Formation of Empty Space in Silicon (ESS) Induced by Silicon Surface Migration” “IEDM: International Electron Devices Meeting” 1999 TECHNICAL DIGEST, p. 517–520, T. Sato “SON (Silicon on Nothing) MOSFET using ESS (Empty Space in Silicon) technique for SoC applications” “IEDM: International Electron Devices Meeting” 2001 TECHNICAL DIGEST, p. 809–812). According to the method, the surface of a substrate having trench is formed with a silicon layer by hydrogen annealing. The silicon layer thus formed closes the upper portion of the trench so that the trench inside has a hollow structure.
However, a large amount of the single SON structures is arranged, and thereby, wasteful regions are formed between elements; as a result, chip area efficiency reduces. For this reason, the element having the SON structure must be formed into a large scale. However, it is difficult to form practical and large-scale hollow structure; for this reason, it is hard to realize a ULSI using the SON structure.
Recently, a study has been made of the so-called system-on-a-chip technique of embedding several systems in one chip to achieve downsizing and high performance. However, if a high performance inductor is formed on a silicon substrate, eddy currents generated in the silicon substrate reduce the inductor characteristics. For this reason, it is difficult to form the inductor on a silicon substrate. In addition, if digital and analog circuits are embedded in one chip, there is a problem that crosstalk occurs between these circuits. In addition, when forming a partial SOI substrate in which an SOI (silicon On Insulator) region is formed at part of the substrate, the shape of the boundary region between the SOI region and bulk region is not preferable. As a result, there is a problem that trouble occurs in the process after that. Therefore, it is desired to develop a semiconductor device, which can form an element having a large-scale hollow region suitable to a system on a chip, and a method of manufacturing the same.